A material having an excellent balance of various properties such as a processability at molding, the dimension precision of a molded article, the mechanical properties such as tensile strength, bending strength and the like, a thermal resistance and the like is demanded for application field such as OA equipments, home electronics products and the like. Especially, the enhancement of the balance of a plane impact strength and a rigidity is requested further for an armoring material. This request becomes recently to a higher level still more.
Besides, high level of a plane impact strength and a rigidity is requested for using as a packaging material. In case of using as a cushioning material, an excellent impact-absorbing property is mentioned as one of essential characteristics to be possessed.
However, a rubber-modified styrenic resin composition was not always sufficient to all of the above-mentioned requests. The reason was that a plane impact strength and a rigidity were antipodal properties and when one increased, another decreased and therefore, it was difficult to keep the both properties to a high level.
A method increasing a rigidity and a specific gravity by adding an inorganic filler is widely known but it has a problem that a plane impact strength decreases.
Besides, as a fracture mode at receiving a plane impact, not a brittle fracture but a ductility fracture is preferred. In case of using as an armoring material, it is not preferred that a broken piece of a resin is dispersed when a brittle fracture occurs owing to an impact. However, the greater part of a rubber-modified styrenic resin composition is destroyed in a brittle fracture mode. A rubber-modified styrenic resin composition containing a large amount of soft components is sometimes destroyed in a ductile fracture mode but it has a problem that a rigidity and a gloss are inferior.
As the results of the present inventors's intensive researches and investigations on the above-described problems, the present inventors attained the present invention.